Inhalation Anesthesia 3 Flashcards
What happens to MAP with increases in concentration of des/iso/sevo in dose dependent manner?
MAP decreases
What effects does N2O have on BP?
Unchanged or even mildly increased MAP.
What effect does halothane have on MAP and CO?
Decreases MAP by decreasing CO.
Isoflurane, a linear dose dependent increase in HR after what MAC?
0.25 MAC
What are HR effects of sevoflurane?
HR does not increase until concentrations >1.5MAC
What are the studied effects of desflurane on HR?
Min increase in HR <1 MAC.
At >1MAC, linear dose dependent increase in HR is observed
What are the more clinical experiences with desflurane on HR?
When you overpressurize you will see some significant tachycardia.
What is the calculation to determine if tachycardia will be seen with desflurane adminsitration?
If percent concentration multiplied by gas flow is greater than 24, you will see tachycardia.
What are the changes seen in cardiac index with inhalation agents?
Minimally influences by inhalation agents.
What effect do inhaled agents have on dysrhythmogenicity (other than halothane)?
Inhaled agents do not predispose the heart to PVCs.
What effect do inhaled agents have on QT interval?
All prolong QT interval, but sevoflurane should be avoided with congenital long QT syndrome
What is coronary steal?
Isoflurane’s ability to dilate small diameter coronary arteries might cause a susceptible patient to develop regional myocardial ischemia as a result of coronary vasodilation.
(not found valid).
What is ischemic preconditioning?
Helps protect the heart by insulting the heart just a little. Gets preconditioned by minor insult then protects the heart from larger ischemic event.
There are two distinct periods of protection, what are they?
First period-
-1-2 hrs after conditioning
Second Period-
- Reappears 24hrs later and can last up to 3 days
What chemically happens that protects the heart in ischemic preconditioning?
Opening of mitchondrial ATP sensitive K+ATP channels.
Without the presence of other agents, what effect do inhalation agents have on RR and TV?
Increased RR and decreased TV.
What happens to MV with inhalation agents?
Stays about the same (>RR,
What happens to chemoreceptors?
Blunted response of central chemoreceptors. May have to get 45-50 before start breathing again.
Which stimulation response is strong: hypoxia or hypercarbia?
Hypoxia, we just don’t use it.
Which agent is “nicest to breathe”?
Sevoflurane, halothane, N2O.
What agents are worst to breath (pungent)?
Desflurane and isoflurane.
What patients should you be cautious using a pungent anesthetics like des and iso?
Asthma, reactive airway disease, COPD, smokers
Which inhalation agents causes increases in CMRO2?
N2O
What changes in CNS effects can be seen around (above or below) 1 MAC?
ICP increases with all anesthetics at > 1 MAC.
Autoregulation is impaired at concentrations 1 < MAC.
Evoked potentials may be abolished at 1 MAC.
Though 0.2-0.3 MAC can decrease the reliability of motor evoked potentials, what other medication actually has a bigger effect?
NMBA
Which inhalation agent will we not use in patients with seizure history?
Sevoflurane
At what MAC might you see isoelectric EEG pattern?
1.5-2.0 MAC
true or false.
Inhalation agents have limited effect on the principle of hypoxic pulmonary vasocontriction?
True
Which agent would you avoid in head trauma/intracranial processes?
N2O
Which medication can counteract the negative effects of N2O in intracranial processes?
Barbs, opiods, or propofol
What happens to autoregulation <1 MAC?
It is impaired
What MAC do Hamot surgeons allow for checking evoked potentials?
1 MAC
True or false:
Inhalation agents produce a dose dependent skeletal muscle relaxation and enhance the activity of NMBA?
True.
Can also be helpful on emergence. As gas comes off, NMBA effects will decrease.
Which agents trigger MH?
Halothane>Forane (isoflurane),>Sevoflurane>Desflurane
Which agents have hepatic effects/injury?
Halothane>sevoflurane>desflurane=iso=enflurane
Renal effects are seen with what agent?
Sevoflurane
What is produced from the breakdown of sevoflurane?
Compound A.
What does the package insert say about sevo administration and renal effects?
If FGF <2L/min, must keep MAC fas flow to max of 2 hrs.
Which agent is contraindicated in pneumothorax?
N2O
Which deficiency would contraindicate N2O?
B12 Deficiency
What is the blood:gas coefficient of the anesthetic gases?
N2O=0.47 Des=0.45 Sevo=0.65 Iso=1.4 Halo=2.3
When an air filled cavity has a compliant wall, what increases with N2O administration?
Volume
When an air filled cavity has a non-compliant wall, what increases with N2O administration?
Pressure
Degradation of CO2 Absorbent creates an exothermic or endothermic process?
Exothermic process (releases heat)
Which agent has a specifically high production of compound A?
Sevoflurane
What complications can arise from iso and des administration with a dessicated absorbent?
Can produce Carbon Monoxide
What actions can prevent exothermic reactions or excess compound A production?
PREVENTION: Adequate hydration is key. -change CO2 absorbent often. -Turn FGF down or off during breaks. -Limit FGF during cases. -When in doubt, change it.
What is the vapor pressure of des at sea level and 20 degrees C?
700mmHg
TEC 6 vaporizer heats desflurane to how many ATM?
2 ATM
Formula to calculate for changes in altitude?
(Desired vaporizer setting at sea level) x (760mmHg) / (Current ATM)
